As communications technologies play an increasingly important role in human life, an overall requirement on communications technologies increases with each passing day in modern society. To improve overall performance of a communications system, numerous new services have emerged in recent years, including enhanced inter-cell interference coordination (eICIC for short), coordinated multipoint transmission/reception (CoMP for short), network-assisted interference cancellation and suppression (NAICS for short), and the like. For all these services, interference is reduced by means of time domain coordination. This requires time synchronization to be maintained between base stations, so as to improve overall system performance.
In the prior art, air-interface synchronization between large and small stations is generally implemented by means of network listening. An implementation is as follows: A synchronization station listens to a reference signal sent by a source station (that is, a reference station), and the synchronization station adjusts, according to time synchronization information carried in the reference signal, time for sending a signal to user equipment (UE). This means that the synchronization station is to subsequently send a signal by using time of the source station as a reference, so as to maintain synchronization when signals are received and sent between stations. However, when there is a relatively long distance between stations, transmission time for the reference signal is no longer ignorable. In this case, using the existing synchronization solution greatly decreases accuracy of synchronization between stations. In addition, because time of the synchronization station itself is not adjusted, absolute time synchronization is not implemented between stations.